Method of making 2:4-dimethyl-6-ethoxyquinoline



UNITED STATES- fiANS '1'. CLARKE AND ERNEST R. TAYLOR,

PATENTOFFICE- OF ROCHESTER, NEW YORK, ASSIGN'OBS TO EASTMAN KODAK COMPANY. OF ROCHESTEE NEW YORK, A CORPORATION OF NEW YORK.

No Drawing.

This invention relates to an improved method for the production of 2 :4-dimethylfi-ethoxyquinoline.

This material is the principal ingredient in 5 the manufacture of the sensitizing dye known.

as dicyanin, and hitherto has been produced only by a troublesome process, involving the action of a mixture of acetone and acetaldehyde or its equivalent upon p-phenetidine in the presence of hydrochloric acid. The yield attained is poor and the isolation of the product is extremely tedious.

We have found that the same product can be made in a two step process, each of the 1 ste s being simple, and a comparatively high yie d obtained.

The first step comprises the interact1on of p-phenetidine with acetone in the presence of a suitable catalyst, such as iodine, yieldlng a compound, presumably p-ethoxyacetoneanil, which can be readily isolated by fractional distillation.

The second step comprises the conversion of this compound into the desired product by heating in a current of hydrogen chloride.

The quinoline derivative may readily be isolated by fractional distillation and purified by recrystallization. We will now proceed to give detailed instructions for carrying out the complete process.

Application filed July 7,

1923. Serial No. 650,427.

The following ingredients are mixed: Grams.

p-phenetidine 3675 Acetone 740 Iodine 25 to the reaction mixture which is boiled under a reflux condenser for 36 hours, the temperature being about 107. v

After further distilling ofi:' acetone and Water, as before, until the temperature of the reaction mixture reaches 140 (1., the mixture, after cooling, is washed with dilute sodium hydroxide.

' It is then submitted to fractional distillation under reduced pressure, in practice at about 10 mm. pressure when a phenetidid compound, presumably p-ethoxyacetoneanil, is distilled over at a temperature of from 165 to 180.

The reaction involved in the above step is believed to be as follows:

I NH: O C

CzHnO OH: N-c 4 \CH:

CIHIO/ (mo) made, but we find the number given above to be most eliicient as a practical process.

In the second step of the process we take, at a time, 150 grams ofthe distillate. This is heated to between 180 and 200 C., for

instance in a large flask in asuitable bath, and dry hydrogen chloride is passed over the surface of the liquid for about 8 hours. This time may be varied considerably, but we attain the most satisfactory results in the time stated. Methane is. evolved. The final mix? ture is dissolved in hot Water and the impurities extracted with benzene. The benzene is separated off, and the water layer treated with an excess of sodium hydroxide. The oils which separate are extracted with ether or benzene. The solvent is distilled OE and the residue distilled under reduced Having thus described our invention, what We claim as new and desire to secure by Letters Patent is:

The herein described process that comprises the steps of acting on p-phenetidine with acetone in the presence of iodine to produce p-ethoxyacetoneanil and the heating of pressure; for example at 168 to 180 at 10 mm. pressure. This yields the desired product 2: l dimethyl 6 ethoxyquinoline which may be purified by recrystallization.

The reaction involved in the above step isbelieved to be as follows CH4 i l C2H5O 

